Receiving circuit



July 7, 1931. H. D. cuRRlr-:R 1,813,232

RECEIVING CIRCUIT Filed April 50, 1925 N ZYL/zY-TUT" rEmEEuPrzPJ-t ZZPney.

Patented July 7, 1931 UNITED STATES PATENT OFFICE HIRAM D. CORBIER, F CHICAGO, ILLINOIS, ASSIGNOR TO '.KELLOGG SWITCHBOARD AND' SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS RECEIVING CIRCUIT Application filed April 30, 1925. Serial No. 26,835.

My invention relates to radio circuits and apparatus for use in Wireless telegraphy and telephony systems, and resides in novel circuit arrangements and apparatus for such systems.

My invention as shown is adapted for the reception of radio signals, but it is to be understood that it may be used for other than receptive purposes. It is an object 3U, of my invention to provide a novel and nals received.

My invention as illustrated in the drawings is shown in a receiving circuit arrangement, having radio frequency amplification, detection and audio frequency amplification, and is particularly illustrated in an arrangement in which inductances are varied to tune the stages of radio frequency amplification.

A feature of the invention resides in my method of varying the inductance of the secondaries of the transformers, to tune the set over the band of Wave lengths, Which it is adapted to receive.

A feature of my invention resides in the simplified control of the tuning arrangement.

A still further feature of my invention resides in the construction, arrangement and control of the apparatus used in my system. I vary the inductance of the secondaries of the couplers or transformers in steps, by means of a multiple control arrangement, and I vary the inductance Within the steps of inductance by means of a separate multiple control arrangement.

A still further feature of my invention is the provision of a multiple, unit control tuning arrangement which provides large movement of the tuning device for a small variation in tuning inductance. In place of resonating the secondaries of the transformers by individual condensers, I vary the inductance of the secondaries of the transformers, by both a multiple step control arrangement and a second multiple control arrangement, for varying the inductances of said secondaries within the steps of variation brought about by the step control arrangement, thereby securing many degrees of movement for said second control device over the Wave band which the set is adapted to receive.

For a more complete understanding of my invention reference may be had to the accompanying drawings in which like reference characters in the different views denote like parts and in which:

Fig. l is a diagrammatic circuit arrangement of my invention;

Fig. 2k diagrammatically illustrates my method of varying the inductance by steps;

Fig. 3 diagrammatically illustrates my method of varying the inductances Within the different steps of inductance; and

Fig. 4 illustrates one method of bank Winding in groups the coils upon the stator of the transformer.

Referring to Fig l of the drawing, 2 represents the ordinary antenna or collector device which is connected through the primary 3 of the variable transformer device 4 to ground 5. A secondary of the device is partly Wound on the stator and is partly Wound on the rotor of the varia le transformer. rlhe part of the secondary Winding on the stator of the device is tapped, and the taps are brought out to terminal points, for cooperation with a contact Wiper. The variable transformer and inductance devices G and 7 are similar in construction to that of device 4. rlhe number of turns on the devices, however, may vary.

Referring more particularly to Fig. 8, it will be noted that each of the variable devices 4, G and 7 is provided with a stator tube or supporting device 4, 6 and 7 respectively. Mounted Within the stator devices are rotatable tubes or rotor elements 42, (i2 and 72. The stator coil supporting devices 4', 6 and 7 are provided With brackets 8 in which a rod 9 is rotatably mounted. The rotor coil supporting tubes 42, G2 and 72 are provided with brackets 10, through which the said rod 9 extends. Brackets l() are secured to the rod 9 so that v isl decreased.

when the same is rotated the rotor elements l42, 62 and 72 rotate therewith. These devices are of the 180 degree coupler type, so that the rotors may be rotated 180 degrees until they are in a plane at rightangles to the plane of the stators, Supporting means, for the stator coil supporting inembers 4, 6 and 7 are provided, but are' notV devices may comprise various niimbers of turns, depending upon `tliebandof wave lengths to be received and the operation desired. rlhese turns may Abe bank wound on the stator i is illustrated in Fig. i.

The secondary windings consists of two sections, one section of which is wound on a rotary tube such as 42, and the other section 17, is wound on the stator, such as 4, and

as Lillustrated in Fig; 4.,y The winding 17 may be wound by the bank groiip method of winding, .as illustrated in Fig. 4, 4'and the groups of turns provided rwith taps 18. The taps of the coils are connectedto sta,-

tionary contacts 19, as shown in Figs. 1

and 2.I The number of Vsecondarf turns on the stator uib@ depends upjoa um treedt-h @i the wave band, over which the device is t`o` be operated. Cooperating` with the conn tacts 19 are wipers 20. The wipers 2O 'are connected together by a rod 21. To the switch arm 2 0 ongone of thevtap switches is connected a 'control knob whiei niay be operated to simultaneoiisiy more the wipers 20 lin unison over their Contact points 19. The secondary part oiithewinding 17 is so wound and`V tappeiil and arranged with respect to the primary 3 that when the devlce 1s operated to recelvc the longer wave lengths, the coupling between the primary 3 and the secondary winding 17 is increased, and for the lower wave lengths the couplingbetween the primary winding 3 and the part 17 of the secondary winding y Bridged across the secondaries of the devices are condensers 25. These condensers are preferably Amade variable, but afterthey are vonce adjusted, they may be locked intheir adjusted position and do notneedto be thereafter changed.

From the foregoing description, it will be noted that when the control member is operated to vary the rotors 42,162 and 72, that the position of the parts of the secondary windings of the said rotors are afi changed with respect to the parts of the secondary windings on the stators, thereby sin'iultaneously changing the inductances of the secondaries.

The wipers 2O operate to change the inductance in comparatively coarse steps, while the control knob 15 operates to' varytle indulctance' of the secondaries within thesteps of inductance between taps.

Audiontubes 2G and' 27 are radio amplifiers, audiontube 28wisvthe detector, and audion tubes 29 and 30 are audio frequency amplifiers. These tubes are each provided with the customary grid, plate and cathode elements:v Connected in the grid circuit of 'the detector audion 28 is the usual grid leak 31 and grid 'condenser 32. The grid returns o audi'ons 2 6, 27 and 2S are connected t roiigh the wipers 20 to the conductor 33,- which entends to the middle point 34 on the resistancev 35, which is ,connected across a primary battery 36, which battery is used for furnishing heating current to the filaments or cathodes of the audion tubes. Bridged from point 34 to ground is a by-pass condenser Batt'er'ies 38 are the usual 'seef` ondary or B batteries for furnishing current to the plates of the audion tubes. The audio frequency transformers 39 and 40 are provided with ironcores. cross the primary of audio frequency transformer 39Vis a bypass condenser 41. Rhe'ostatsY 32and 43 control the supply of heatingfcurrentto audion tubes 26 and 27 respectively. Rlieostat 44 controls the sup; ply of 'heating' current to thel filamentV of audion tube 28, and rh'eostat 45 controls the Supply of Beating @maar e@ the filaments of audion-tubes 29 andl 30. kAt 46 show a pair of receivers in theV plate circuit of the l audion tube, for receptive piirposes, however, the device 4e may be reputed by the iisimiiud speaker new in se Before the sa is Lapiedra regular us, the con'densers v25- are adjusted so thatthey need not be touched after once adjusted and locked in their' adjusted positions. The knob 22 is operated to place switch wipers 20 upon one of ycor-.itact 4points 19, thereby rendering effective a certain ainunt of the stationaryvpart 17 of the secondary windings. The individual condensers 25 are then adjustedto bring in the test :signal `with the' maximum clearness and v'o'l'unie. After this adjustment of the condensers 25 is 'once' made the rotor plates thereof are locked in their adjusted position, and remain v.set in sch position. To tune the Vset to different 'Wave lengths, the wipers 20 are set on the Contact points which include tlrewave length of the band within which the desired wave length appears, and then the in'duc'tan'ce .of the se'condaries is varied, minii't'ely, by the turning` of the knobor dial 15 until the combinationof the inductances of the secondaries and the condensers 25 are such as to pass the frequency of the desired wave length, Of course, it is necessary to adjust the rh'eostats until the correct amount of heating current is supplied to the filaments of the vvarious tubes. On the longer wave lengths the coupling between the primary and the stator -part of the secondary is increased for reasons well understood.

I/Vith my arrangement I have found that a very fine tuning may be obtained for the reasons that the inductances of the secondaries may be varied very slightly, owing to the fact that the couplers are of the 18() degree type and provide 180 degree movement for the band of wave lengths included between adjacent taps of the tap switches. In other words for each point that the tap switch may be moved to, the control dial l5 may be operated 180 degrees to vary the inductances between the adjacent taps, thereby permitting the obtaining of a very fine adjustment.

My arrangement clearly simplifies the tuning, as it is only necessary to operate the control lmob 22 to change the inductance of the secondaries by steps and to then operate control dial or knob l5 to select the desired stations within the selected band of wave lengths.

Briefly the incoming oscillations are received by the collector 2 and are passed through the primary of the first transformer, which operates to induce the same into the secondary thereof and upon the grid of the audion tube 26. The signal is operative upon the grid of the tube 26 to repeat the same through the primary of transformer device 6 by means of the plate of tube 26. The signal is then inductively transferred into the secondary of the transformer 6 and is operative upon the grid of the tube 27 to repeat the signal from the plate of tub-e 27 through the primary of transformer 7. The signal is again repeated and amplified inthe tube 28, which tube operates. to pass the signal through the primary of the audio frequency transformer 39 and on through the audion tubes 29 and 80 and audio frequency transformer 40 to the receiving device 46. The tuning of the seconda 1ies of transformers Ll, G and 7 permits only the passage of the desired signal. The secondaries of the transformers and the condensers 25 being in multiple, and the inductance of the secondary being variable by steps and continuously between steps, permits the resonating of the secondaries of the transformers to the desired frequency.

I find that inductances may bc constructed to follow each other very closely thereby permitting the multiple tuning of the same without noticeable difference between the different stages after condensers 25 have once been set to resonate the circuit to the test signal.

The preceding description and explanation will enable one skilled in the art to practice the invention, and the analysis given, is believed to indicate the principal effects involved in the results obtained.

While I have illustrated and described one specific embodiment of my invention, it is to be understood that I do not desire to be limited to the exact matter shown, but aim to cover all that which comes within tle spirit and scope of the appended claims.

What I claim as new and desire to secure by United States Letters Patent, is:

l. A cascade receiving circuit of the character described including a plurality of audion tubes, a plurality of transformers associated with said tubes and having primary windings and adjustable secondary windings, condensers bridged across said secondary windings, and means for adjusting said secondaries by steps and by rotating portions of said secondary windings relative to other portions thereof to tune the said secondary windings to desired frequencies.

2. A cascade receiving circuit of the character described including a plurality of audion tubes, a plurality of transformers associated with said tubes and having primary windings and secondary windings, condensers bridged across said secondaries, and means for simultaneously adjusting said sccondaries by controlling the number of turns thereof in effective relation to the primaries and by rotating portions of said secondary windings relative to other portions thereof to tune the said secondary windings to predetermined frequencies.

3. A cascade receiving circuit of the character described including a plurality of interrelated audion tubes and transformers, primary and secondary windings for said transformers, condensers bridged across said secondary windings, and means for individually setting said condensers to resonate the said secondaries to a predetermined frequency, and means for varying the inductance of said secondary windings by steps and between steps to tune the same.

t. A multiple stage receiving circuit of the character described including a plurality of interrelated audion tubes and transformers, primary and secondary windings for said transformers, condensers bridged across said secondary windings, and means for individually setting said condensers to resonate the said secondaries to a predetermined frequency, and means for simultaneously varying the inductance of said secondary windings first by coarse adjustment and then by fine adjustment to resonate the same to predetermined desired frequencies.

5. A multiple stage receiving circuit of the character described including a plurality of transformers having primary windings and adjustable secondary windings, au-

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dion tubes associated with said transformers, vcondenser-s bridged across said secondary windings, and means for varying the inductance of said secondary windings step by step and continuously between steps to tune said secondary windings.v

6. A cascade receiving arrangement of the character described involving ak plurality of stages of radio frequency amplification including Aa plurality `of transformers, yand means for varying the inductance of said transformers by :steps and Acontinuously 'between steps to tune the same to desired frequencies so that said stages operate as cascade amplifying filters.

7. A receiving arrangement of the character -described involvingr a plurality of stages of radio frequency amplificati-on including a plurality of transformers, secondary windings for said transformers having movable portions and stationary portions, and means for simultaneously varying the inductance of said transformers by larger amounts and then by smaller amounts to tune the same to the desired frequency by operating the movable portions of said secondary windings.Y

8. A receiving circuit of the character described including a plurality of audion tubes, a plurality of transformers having primary and secondary windings associated with said tubes, means for simultaneously varying the inductance of said secondary windings and for increasing the coupling between said secondary windings 'and said primary windings, and separate means for varying the inductance of said secondary windings.

9. A multiple receiving circuit of the character described including a plurality of audion tubes a plurality of transformers having primary and secondary windings associated with said tubes, a common means for varying the inductance of said secondary windings by steps and for increasing ythe coupling between said secondary windings and said primary windings, and separate means for simultaneously varying the inductance of said secondary windings.

l0. A receiving arrangement of the character described including a cascade amplifying arrangement provided with transformers having primary and secondary windings, audion tubes connected between said transformers, a control device for varying the inductance of said transformers by steps, Iand an independent control device for gradually and continuously varying the inductance` of said transformers.

11. A cascade amplifying arrangement for receiving signals of different frequencies, asingle control unit for adjusting said amplifying 4arrangement by steps, and a second singie control unit for continuously adjusting said amplifying arrangement between steps.

l2. A multiple receiving 'circuit provided with :a plurality of stages of amplification, means for :tu-ning said stages of amplification, a single control device for adjusting said means by steps, and a second single control device for continuously adjusting said means lbetween steps.

13. A transformer of the character described including a stator portion and a rotor portion, a primary winding for said transformer mounted on said stator portion, a secondary winding for said transformer partly mounted on said stator portion and partly on said rotor portion, 'a tap switch for the portieri of said winding mounted on said stator support, said portion of said winning mounted on said stator support being so related to said primary winding that the tap switch increases the number of turns operative of said secondary winding the coupling between said primary winding and said secondary winding is increased.

lsf. A cascade receiving arrangement of the character described including a plurality of stages of amplification, a transformer for each of said stages of amplification hav.- ing a secondary winding, said secondary windings comprising tapped fixed portions and movable portions, a condenser connected across each of said secondary windings, and means for varying the inductance of said secondary windings by adjusting said movable portions thereof to resonate said windings for Athe passage of a current of a given frequency.

l5. A cascade amplifying arrangement of the character' described including a plurality of transformers having primary and secondary windings, a condenser bridged across each of said secondary windings, and a multiple control device for changing the inductance of said secondary windings by steps and continuously between. steps to resonate them for the passage of a current of a given frequency.

1G. A cascade amplifying arrangement of l the character described including a plurality of transformers having primary and secondary windings, a condenser bridged across each of said secondary windings, a common device for changing the inductance of said secondary windings, and a second common device for independently continuously changing 'the inductance of said secondary windings.

17. A cascade radio receiving arrangement comprising a plurality of stages of amplifying filters including audion amplifiers and transformers, circuit connections between said transformers and audion amplifiers, each of said transformers comprising a fixed primary winding and a secondary winding including a fixed portion and a movabie portion, means for simultaneously varying the number of turns of the fixed portions of said secondaries effectively related to said primaries, and other means for simultaneously varying the movable portions of said secondaries to simultaneously resonate said secondaries to receive a current of a predetermined frequency, means for detecting said current, and means for thereafter amplifying the same at audio frequency.

Signed by me at Chicago, county of Cook, and State of Illinois, this 28th day of April, 1925.

HIRAM D. CURRIER. 

